Impurities in marbles from the deposits in Petrovac na Mlavi, near Gostivar (Duf and Sušički Most) and Venčac in Yugoslavia
have been determined by activation analysis. The impurities of Na, Mn and Cu were determined from the characteristic photopeaks
with γ-energies of 1.38 and 2.78 MeV (
24Na); 0.511 MeV (
64Cu) and 0.850 MeV (
56Mn), and from the corresponding half-lives of these radioisotopes. The concentrations of Mn, Na and Cu were also determined
in every marble sample.